Having aggression problems

I have a Bassett/border collie mix who is developing some bad habits. She is suddenly becoming very territorial concerning her food and the space around her crate sometimes. (she is fed and watered inside her cage because she's not allowed to run around the house) She's very weird about her food; she intentionally spills it every time it's given to her, and shoves her bed and toys at it, but if you take it away, she gobbles up the stray pieces like she was starving.
At first I thought it was just that she hates the broom because she goes ballistic when you use the broom to sweep up what she's spilled, but now she does the same when my mom picks it up, and sometimes when I do. In one instance, she kept going off and growling just when my mom walked by her crate, or was doing something very near it. She's never bitten anyone and I can still take and handle her things without her biting or anything, but I need to know how to make this behavior stop altogether, especially before it gets worse. Anybody have any advice???:confused:

How old is she? Have you done obedience training with her? How long have you had her?